U  G 


V 


UC-NRLF 


$C    IE    502 


ILITARY  S] 


ING 


A  NO 


MAP  READING 


FOR 


NON-COMMISSIONED  OFFICERS 


GRIEVES 


*'*•«» 


MILITARY  SKETCHING 

AND 

MAP  READING 

FOR 

NON-COMMISSIONED  OFFICERS 

(Illustrated) 


BY 

FIRST  LffiUTENANT  LOREN  C.  GRIEVES 

30th  Infantry 


Fourth  Edition 


WASHINGTON 

UNITED  STATES  INFANTRY  ASSOCIATION 

1916 


Copyright,  1915 
ByJLieut.  Loren  C.  Grieves 


National  Capital  Press.  Inc. 

Book  llANurAcruiras 

Washington.  D.  C. 


TABLE  OF  CONTENTS 

PAGES 

INTRODUCTION 7 

LESSON  I 
Importance  of  Military  Sketching  and  Map  Reading 8 

LESSON  II 
Length  of  Pace  and  Scales  of  Paces. . 9-12 

LESSON  III 
The  Compass  and  Declination  of  the  Needle 13-15 

LESSON  IV 

Distances  and  Directions 16-18 

LESSON  V 
Distances  and  Directions,  Continued. — Location  of  Points  by  Intersection 

and  Resection. — Practical  Method  of  Representing  Ground  Features. .        19-23 

LESSON  VI 
Conventional  Signs 24-30 

LESSON  VII 
Conventional  Signs,  Continued 31-32 

LESSON  VIII 
Distances  and  Directions,  Continued. — Map  Reading 33-36 

LESSON  IX 
Elevations. — Contours. — Construction  of  Model  to  Illustrate  Contours 37-39 

LESSON  X 
Orientation  and  Map  Reading 40-41 

LESSONS  XI  AND  XII 
The  Game  of  "Hide  and  Seek" 42-44 

LESSON  XIII 
Measurement  of  Angles  of  Slope. — Construction  of  Slope  Board. — Scale  of 

Map  Distances 45-47 

LESSON  XTV 
Profile  Method  of  Spacing  Contours 48-50 

LESSONS  XV,  XVI,  AND  XVII 
Contouring,  Continued 51 

LESSONS  XVIII  AND  XIX 
The  Road  Sketch  Complete 52-55 

LESSON  XX 
The  Position  Sketch 56-59 

333682 


INTRODUCTION 


General  Principles 

This  text  treats  of  that  portion  of  Military  Topography  included  in  the  subjects 
of  Military  Topographical  Sketching  and  Military  Map  Reading. 

Military  Topographical  Sketching  treats  of  Military  Road  and  Area  Sketches 
and  methods  involved,  while  Military  Map  Reading  pertains  to  the  correct  inter- 
pretation of  all  features  represented  on  these  sketches. 

The  two  subjects,  in  so  far  as  they  are  treated  in  this  text,  may  be  called  the 
"Married  Pair,"  they  go  hand  in  hand.  In  order  to  efficiently  perform  the  duties 
pertaining  to  the  office,  it  is  absolutely  essential  that  every  non-commissioned  officer 
possess  a  working  knowledge  of  both  subjects. 

This  text  makes  no  distinct  division  of  its  course  of  instruction  in  Military 
Sketching  and  Map  Reading;  as  one  is  taught,  the  other  is  learned;  the  latter  proves 
the  former. 

The  average  non-commissioned  officer,  after  a  conscientious  study  of  the  follow- 
ing thirty  lessons  should  be  able  to  construct  a  road  or  an  area  sketch,  and  should 
possess  a  knowledge  of  Military  Map  Reading  sufficient  to  enable  him  to  readily 
interpret  any  topographical  military  map. 

Before  entering  upon  this  course,  the  instructor  should  secure  a  sufficient  amount 
of  the  following  articles  to  supply  the  class:  pencils,  (Faber's  HHHH,  HHHHHH 
and  HB),  erasers,  profile  paper,  tracing  paper,  and  the  best  available  military  maps 
of  the  surrounding  country.  Each  member  of  the  class  should  be  equipped  with  a 
compass.  See  Appendix  for  the  construction  of  drawing-board  with  tripod  and 
attachment  for  reading  angles  of  slope.  The  Universal  Rule  for  Military  Sketching 
and  Map  Reading  fulfills  all  other  needs  of  the  student  of  this  subject  such  as  working 
and  reading  scales,  scales  of  map  distances,  protractor,  means  of  drawing  perpendi- 
cular and  parallel  lines,  rates  of  speed  per  minute  of  various  arms  of  the  service,  an 
easy  method  of  solving  all  visibility  problems,  memorandum  pad  and  message  blank. 
The  Universal  Rule  is  furnished  with  each  copy  of  this  book. 

The  instructor  should  anticipate  the  requirements  of  each  lesson  and  have  the 
necessary  paraphernalia  on  hand,  for  example,  the  drawing-boards  and  tripods  should 
be  completed  before  Lesson  IV,  the  attachments  for  reading  angles  of  slope  should 
be  completed  before  Lesson  XIII  and  the  Model  of  Map  A  and  sand-table  should 
be  constructed  before  Lesson  IX. 

Finally,  the  instructor  should  bear  in  mind  that  his  class  will  not  obtain  the 
desired  results  of  this  course  without  his  enthusiastic  and  intelligent  co-operation. 


MILITARY  SKETCHING  AND   MAP  READING 


LESSON  I 


Importance  of  Military  Sketching  and  Map  Reading 

It  is  said  that  one-half  of  the  people  who  read  a  book  never  read  the  preface 
nor  the  introduction.  Before  starting  on  this  course,  a  part  of  the  first  lesson  should 
be  devoted  to  carefully  reading  the  preface  and  introduction,  this  to  enable  the 
student  to  gain  an  idea  of  the  scope  of  the  course  which  he  is  about  to  study,  also 
that  instructor  and  student  may  each  know  what  is  expected  of  the  other. 

In  order  to  render  his  country  efficient  service  in  time  of  need,  it  is  absolutely 
necessary  that  every  non-commissioned  officer  be  able  to  construct  a  road  and  an 
area  sketch,  and  that  he  be  able  to  read  a  military  topographical  map.  You  are 
sent  to  a  certain  point  to  observe  and  report.  In  no  way  other  than  by  making  a 
sketch  can  you  properly  convey  to  your  commanding  officer  what  you  have  seen. 

In  order  to  demonstrate  the  urgent  necessity  of  a  knowledge  of  military  sketching, 
the  instructor  should  take  the  class  to  a  point  possessing  a  good  view  of  country 
covered  with  a  variety  of  natural  and  artificial  ground  features.  After  studying 
the  landscape  for  ten  or  fifteen  minutes,  members  of  the  class  will  face  away  from 
the  country  just  observed  and  make  a  written  report  of  what  they  have  seen:  loca- 
tions and  directions  of  hills,  valleys,  rivers,  roads,  railroads,  telephone  and  telegraph 
lines,  locations  and  dimensions  of  bridges,  buildings,  etc. 

The  instructor  will  then  verify  these  reports  in  the  presence  of  the  class,  noting 
all  errors  and  omissions.  This  will  serve  as  an  object  lesson  of  the  importance  of  a 
knowledge  of  Military  Sketching. 

Let  us  imagine  two  non-commissioned  officers,  equally  brave  and  alert,  possess- 
ing equal  military  qualifications  with  the  exception  that  one  is  able  to  read  a  map 
accurately  and  the  other  knows  nothing  of  this  important  military  accomplishment. 
These  men  are  sent  out  with  detachments  on  similar  important  missions  in  time  of 
war.  They  are  both  brave,  both  alert,  but  one  is  absolutely  sure  of  the  road  or  trail 
that  he  is  taking,  while  the  other,  unfortunately,  is  not;  he  has  misgivings,  he  begins 
to  lose  confidence  in  himself  and  his  men  lose  confidence  in  him.  Brave  as  he  is, 
the  element  of  uncertainty  prevails,  he  loses  assurance  and  likewise  the  trail,  and 
leads  his  detachment  to  disaster.  The  other  man  is  positive,  retains  his  bravery  and 
the  respect  and  confidence  of  his  men  and  leads  them  to  success. 

The  main  object  of  this  lesson  is  to  instill  in  the  mind  of  each  member  of  the 
class  that  to  be  a  leader  and  give  the  best  service  to  his  country  he  must  acquire  a 
working  knowledge  of  Military  Sketching  and  Map  Reading. 


FOR  NON-COMMISSIONED  OFFICERS 


LESSON  II 


Length  of  Pace  and  Scales  of  Paces 

Each  member  of  the  class,  in  order  to  determine  the  length  of  his  pace,  should 
pace  some  known  course  near  his  station,  as  for  example,  a  thousand  yards  on  the 
target  range. 

While  pacing  one  should  walk  at  an  easy,  natural  and  uniform  gait.  This  is 
important  as  there  is  always  a  tendency  for  the  beginner  to  consider  pacing  and 
his  ordinary  gait  as  entirely  distinct  which  usually  results  in  his  first  scale  of  paces 
being  too  long.  This  may  be  obviated  by  pacing  a  sufficiently  long  course  several 
times,  first  impressing  upon  the  student's  mind  the  necessity  of  taking  a  perfectly 
natural  and  uniform  gait. 

Each  man  will  pace  the  course  four  times.  Suppose  that  his  four  results  of 
pacing  a  course  1000  yards  long  are: 


1118 

paces. 

1109 

ii 

1120 

ii 

1117 

ii 

Total  4464  paces. 
4464-^-4=1116  paces  (average  number  of  his  paces  for  1000  yards). 

To  determine  the  length  of  his  pace  in  inches: 
1000  yards  =  36000  inches. 
36000 -=-1116  =  32.2  inches,  the  length  of  his  pace. 

Having  determined  the  length  of  pace  let  us  now  consider  the  subject  of  scales 
of  maps.  It  is  very  clear  that  the  ground  and  all  of  the  objects  upon  it  cannot  be 
represented  as  large  on  the  map  as  they  actually  are.  They  must  be  reduced  in 
size.  In  other  words,  any  distance  on  the  map  is  a  certain  fixed  part  of  the  corre- 
sponding distance  on  the  ground,  and  this  relation  between  map  distance  and  ground 
distance  is  called  the  scale  of  the  map. 

The  scale  should  be  no  larger  than  is  necessary  to  bring  out  all  of  the  required 
details.  For  example,  it  has  been  found  that  the  scale  3  inches  =  1  mile,  (meaning 
that  3  inches  on  the  map  represents  one  mile  on  the  ground),  is  the  proper  scale  for 
road  sketches.  It  gives  just  enough  room  to  insert  all  of  the  details  of  military 
importance,  while,  if  we  were  to  use  the  scale  1  inch  =  1  mile  for  road  sketches,  there 
would  not  be  enough  room,  and  by  using  the  scale  6  inches  =one  mile  we  would 
burden  ourselves  and  those  reading  the  map  with  an  unnecessary  amount  of  paper. 

There  are  three  ways  in  which  the  scales  of  maps  may  be  represented: 

1st.    A  plain  statement,  as  for  example,  3  inches  =1  mile. 


io  .  Military  Sketching  and  Map  Reading 

2nd.  Represented  by  a  fraction.  To  determine  the  fraction  representing  any 
scale,  as  3  inches  =  1  mile,  let  the  map  distance  be  the  numerator  and  the  ground 
distance  the  denominator,  both  terms  of  the  fraction  being  of  the  same  denomina- 
tion, then  reduce  the  fraction  so  that  the  numerator  will  be  unity,  as  for  example: 

3  inches  on  map        3  inches  1 

= = =  Representative  Fraction  (abbreviated  R.  F.). 

1  mile  on  ground     63360  inches    21120 

3rd.  Graphically,  in  which  the  scale  is  actually  represented  on  the  map  or  on 
a  ruler  by  a  line  divided  into  equal  parts,  each  division  being  marked  by  the  dis- 
tance which  it  represents  on  the  ground. 

There  are  two  kinds  of  graphical  scales:  one  for  making  the  map,  called  the 
working  scale,  and  one  for  reading  the  map,  called  the  reading  scale.  If  the  same 
units  of  measure  were  used  for  both  map  making  and  map  reading,  one  scale  would 
answer  for  both  purposes,  but  this  is  seldom  the  case  as  we  may  obtain  our  distance 
in  terms  of  paces  or  strides  of  various  lengths  depending  upon  the  individual,  while 
the  party  reading  the  map  necessarily  must  have  the  distance  expressed  in  terms 
of  well  known  units  as  yards  or  miles. 

In  order  to  be  able  to  make  a  map  or  read  a  map  we  must  have  in  our  possession 
the  proper  working  and  reading  scales.  With  each  copy  of  this  book  is  a  Universal 
Rule  for  Military  Sketching  and  Map  Reading.  On  this  rule  are  blank  spaces  to 
inscribe  one  inch,  three  inch  and  six  inch  scales  of  paces.  Figs.  I  and  II  show  scales 
for  different  lengths  of  paces  or  strides.  Any  desired  scale  may  be  copied  from  these 
plates  by  placing  the  edge  of  the  Universal  Rule  on  the  proper  line  or  by  interpolating 
between  the  lines. 

After  each  man  has  determined  the  length  of  his  pace  the  following  scales: 

1  inch     =  1  mile. 
3  inches = 1     " 
6inches=l     " 

should  be  inscribed  on  his  Universal  Rule  as  indicated  above.  Small  grooves  should 
be  made  with  a  sharp  knife  to  indicate  the  divisions  of  the  scale,  and  these  grooves 
marked  with  black,  water-proof,  India  ink,  using  a  crow-quill  pen. 

Either  the  instructor  or  some  member  of  the  class  who  is  a  fair  draftsman  should 
inscribe  the  scales  on  the  rules.  When  the  scales  are  once  transferred  to  the  rules, 
these  rules  should  be  considered  just  as  much  a  part  of  the  non-commissioned 
officer's  equipment  as  his  canteen. 

On  the  Universal  Rule  are  reading  scales  of  yards  for  one,  two  and  three  inches 
equals  one  mile.  By  the  aid  of  these  scales  and  multiples  thereof,  a  reading  scale 
in  yards  for  any  map  may  be  quickly  constructed. 

For  a  method  in  detail  of  constructing  scales  see  appendix.  However,  the 
mathematical  amd  mechanical  work  involved  in  constructing  scales  is  no  more  essen- 
tial to  the  instruction  of  non-commissioned  officers  than  the  construction  of  a  compass. 


For  Non-Commissioned  officers 


u 


PACE 
OH    STEP. 

24-    ° 


II2II20  3  In.=1Mi. 

24    26     28    3000 


lOO 
6in.Mmi.  0 
lin.-lmj.  0      3 


1500 
2  3  4  5  6  700    Paces 

12      IS      18     21      24    27     30     33     36    39     4200  Paces 


12 


Military  Sketching  and  Map  reading 


STEP  ON 
STRIDE 


Scale     1:21120  3 IN.*  I  Mi. 

2        3        4       5        6       7        8       9        10      M        12       13      14      1500 


I00~*  0 
6in  «lml.  0 
lin.'lml.  0 


■00  Paces 

500  Paces 

27       3000Paces 


Fig.  2 


FOR  NON-COMMISSIONED  OFFICERS  13 


LESSON  III 


The  Compass  and  Declination  of  the  Needle 

Having  determined  a  means  of  representing  the  map  distance  between  two 
objects  on  the  ground,  it  now  follows  that  we  must  learn  how  to  represent  the  direc- 
tion of  one  object  from  another. 

We  are  able  to  do  this  by  means  of  the  magnetic  compass,  an  instrument  having 
a  light  needle  which  swings  freely  and  comes  to  rest  with  its  north  end  always  point- 
ing to  what  is  known  as  the  magnetic  north.  The  magnetic  north  differs  from  the 
true  north  in  many  localities,  and  moreover  this  discrepancy  is  constantly  changing, 
and  for  this  reason  maps  should  always  have  the  true  as  well  as  the  magnetic  north 
indicated.  The  number  of  degrees  that  the  needle  points  away  from  the  true  north 
is  called  the  DECLINATION  OF  THE  NEEDLE. 

For  accurate  measurement  of  directions,  the  circle  described  by  the  point  of  the 
compass  needle  is  divided  into  360  equal  parts  called  degrees.     (See  Fig.  3.) 

There  are  a  few  simple  methods  of  determining  the  true  meridian  (true  north- 
and-south  line)  with  a  degree  of  accuracy  sufficient  for  military  sketching  and  map 
reading: 

1st. — By  means  of  the  North  Star.  Without  instruments,  it  can  be  determined 
approximately  by  placing  two  cords,  with  weights  attached,  in  line  with  the  Star. 
The  cords  should  be  twelve  feet  apart,  and  to  see  the  forward  one,  it  will  be  necessary 
to  throw  a  light  upon  it.    This  line  can  readily  be  prolonged  by  daylight. 

2nd. — By  aid  of  the  sun  and  plumb-bob  (see  Fig.  4).  On  a  level  piece  of  ground 
lean  a  pole  toward  the  North,  and  rest  it  in  a  crotch  made  by  two  sticks  as  shown. 
Suspend  a  weight  from  the  end  of  the  pole  so  that  it  nearly  touches  the  ground; 
then,  about  an  hour  before  noon,  attach  a  string  to  a  peg  driven  directly  under  the 
weight,  and,  with  a  sharpened  stick  attached  to  the  other  end  of  the  string,  describe 
an  arc  with  a  radius  equal  to  the  distance  from  the  peg  to  the  shadow  of  the  tip  of 
the  pole.  Drive  a  peg  on  the  arc  where  the  shadow  of  the  tip  of  the  pole  rested. 
About  an  hour  after  noon,  watch  the  shadow  on  the  tip  as  it  approaches  the  eastern 
side  of  the  arc,  and  drive  another  peg  at  the  point  where  it  crosses.  By  means  of  a 
tape  or  string  find  the  middle  point  of  the  straight  line  joining  the  last  two  pegs 
mentioned.  A  straight  line  joining  this  middle  point  and  the  peg  under  the  weight 
will  be  in  the  true  meridian. 

Place  a  pole  about  100  yards  in  prolongation  of  this  line,  and  with  the  compass 
sight  back  on  the  tip  of  the  inclined  pole,  and  the  declination  will  be  obtained. 

3rd. — By  aid  of  the  watch  and  sun.  Lay  the  watch  on  some  level  surface,  and 
revolve  it  until  the  hour  hand  points  directly  under  the  sun.  Then  by  reference  to 
the  divisions  on  the  dial,  determine  the  point  on  it  midway  between  the  hour  hand 


14  MILITARY  SKETCHING  AND   MAP  READING 

and  Fig.  XII.     A  line  through  this  point  and  the  pivot  of  the  hands  will  be  approxi- 
mately in  the  true  meridian  (see  Fig.  5). 

The  operation  of  pointing  the  hour  hand  directly  under  the  sun  is  made  easy  by 
casting  the  shadow  of  a  vertical  straw  or  straight  stick  across  the  face  of  the  watch 
and  then  bringing  the  hour  hand  into  this  shadow. 

The  watch  method  will  not  answer  during  certain  seasons  in  the  Tropics  when 
the  sun  passes  directly  overhead. 

There  is  also  another  slight  error  due  to  the  fact  that  in  some  sections  there  is 
a  difference  of  a  half  hour  between  Standard  and  Sunjtime. 

The  class  will  obtain  the  declination  of  the  needle  for  its  particular  locality  by 
all  of  the  above  methods  and  compare  results. 

After  consulting  Fig.  3,  each  man  should  be  required  to  draw  on  the  black-board 
angles  of  various  degrees. 

Imagine  that  you  are  at  the  center  of  the  circle,  Fig.  3.  Determine  the  follow- 
ing directions: 

N   30°  E. 
S    15°  W. 
E    30°  N. 
W  15°  N. 

In  order  to  take  up  the  work  assigned  in  the  following  lesson,  each  sketcher 
should  be  equipped  with  a  compass,  drawing-board  (see  Appendix  for  construction 
drawing-board  with  tripod  and  attachment  for  reading  slopes),  universal  rule,  rubber 
eraser,  pocket  knife,  paper.     Faber  H  or  HB  pencil  and  a  half  dozen  thumb  tacks. 


for  Non-commissioned  Officers 


is 


otz  «* 


.    © 


Fig.  4 


Fig.  5 


16  MILITARY  SKETCHING  AND  MAP  READING 

LESSON  IV 


Distances  and  Directions 

Fig.  6  represents  the  road  A  B  C  D  to  be  sketched. 

On  your  paper  draw  a  straight  line  representing  the  needle  of  the  compass. 
Mark  one  end  of  this  line,  N. 

In  sketching,  always  hold  your  drawing-board  in  such  a  position  that  the  north 
end  of  the  compass  needle  and  the  arrow  end  of  the  needle  indicated  on  the  paper 
are  pointing  in  the  same  direction.  (In  the  future  we  will  refer  to  this  operation 
as  "Orienting  the  board.") 

Go  to  the  point  A  of  the  road.  (See  Fig.  7.)  Orient  the  board.  From  any 
convenient  point  (a)  (one  usually  knows  the  general  direction  of  the  course  to  be 
sketched  and  should  select  a  point  of  beginning  which  will  afford  the  greatest  use 
of  the  paper.  For  example,  if  your  course  takes  you  in  an  easterly  direction,  your 
point  of  beginning  should  be  near  the  west  margin  of  the  paper),  on  the  board  draw 
a  light  straight  line  in  the  direction  A  b.  Next  pace  the  distance  A  to  B,  and  with 
your  scale  of  paces  (3  inches  =  1  mile)  lay  off  the  line  a  b  representing  the  distance 
A  B. 

The  paces  may  be  counted  or  a  pedometer  may  be  used.  In  order  to  avoid 
error  in  counting  paces  a  check  mark  should  be  made  of  each  100  paces. 

The  pedometer  is  a  small  instrument  about  the  size  and  form  of  a  watch  used 
for  recording  the  number  of  steps  taken  in  walking.  By  means  of  a  small  weighted 
lever  which  descends  with  every  step,  motion  is  communicated  to  a  train  of  wheels 
and  the  number  of  steps  is  recorded  on  a  dial  by  pointers. 

Next  orient  the  board  at  B,  draw  a  straight  line  in  the  direction  B  C,  pace  B  C 
and  lay  off  the  line  b  c. 

Orient  the  board  at  C,  draw  a  light  line  in  the  direction  C  D,  pace  C  D  and  lay 
off  the  line  c  d. 

The  instructor  will  require  each  member  of  the  class  to  plot  a  course  having 
several  changes  of  direction.  If  the  drawing-board  is  placed  on  a  tripod  it  will 
greatly  assist  the  beginner  in  determining  an  accurate  line  of  sight.  The  scale  6 
inches  =  1  mile  might  be  used  instead  of  the  3-inch  scale,  thus  making  more  evident 
all  errors  in  distance  and  direction. 

On  returning  to  barracks,  results  will  be  compared  and  errors  pointed  out. 
An  accurate  sketch  of  the  route  taken  should  be  drawn  upon  the  black-board  in 
order  that  each  man's  sketch  may  be  compared  with  it. 


FOR  NON-COMMISSIONED  OFFICERS 


17 


•    - » 


uoou 


ll  1 


im^cdr- 


18 


MILITARY  SKETCHING  AND   MAP  READING 


Fig.  7 


FOR  NON-COMMISSIONED  OFFICERS  19 


LESSON  V 


Distances  and  Directions,  Continued — Location  of  Points  by  Inter- 
section and   Resection — Practical  Method    of 
Representing  Ground  Features 

For  this  lesson  some  course  in  which  the  point  of  beginning  and  ending  are  the 
same  should  be  designated,  as  for  example,  the  course  A  B  C  D  E  F  A — Fig.  8.  This 
will  serve  as  an  excellent  check  upon  the  work.  The  methods  employed  will  be 
the  same  as  in  the  last  lesson  except  that  important  points  to  the  right  or  left  of  the 
course  should  be  located  by  intersection  and  locations  along  the  course  may  be 
verified  by  resection. 

To  locate  a  point  by  intersection,  as  for  example  the  hill,  G,  Fig.  8. — Orient  the 
board  at  A,  Fig.  9,  mark  the  point  (a)  on  the  board  to  correspond  to  A  on  the  ground. 
Sight  in  the  direction  B,  and  from  (a)  draw  a  straight  line  in  the  direction  of  B,  then 
sight  at  the  hill  G,  and  draw  a  straight  line  from  (a)  in  the  direction  of  G.  (Care 
must  be  exercised  to  keep  the  board  constantly  oriented.  In  determining  the  line 
of  sight  from  the  point  of  observation  on  the  map  to  some  distant  point  on  the  ground, 
pivot  the  universal  rule  at  the  point  of  observation  and  sight  along  the  upper  edge 
of  the  rule  toward  the  object  keeping  the  rule  perpendicular  to  the  board.)  Pace  the 
distance  A  B,  orient  the  board  at  B,  and  lay  off  the  map  distance  (ab)  corresponding 
to  the  ground  distance  A  B,  then  sight  at  the  hill  G  and  draw  a  straight  line  from  (b) 
in  the  direction  of  G.  The  lines  drawn  from  (a)  toward  G  and  from  (b)  toward  G 
intersect  at  (g)  which  is  the  map  location  of  the  hill  G.  In  a  similar  manner  any 
other  points  as  G,  H,  and  I  (Fig.  8)  may  be  located  by  intersection  from  any  two 
points. 

Angles  of  less  than  30  degrees  or  greater  than  120  degrees  at  the  point  of  inter- 
section should  be  avoided  as  the  two  intersecting  lines  are  so  nearly  parallel  that  it 
is  difficult  to  locate  the  exact  point  of  intersection. 

To  locate  a  point  by  resection: 

Suppose  that  at  the  point  F  of  the  course  A  B  C  D  E  F  A,  Fig.  8,  you  wish  to 
verify  your  location.  The  points  G  and  A  on  the  ground  have  already  been  correctly 
located  on  the  map  at  (g)  and  (a),  (see  Fig.  10).  The  sketcher  is  at  the  point  F 
which  he  wishes  to  locate  on  his  map.  He  orients  the  board  with  the  compass, 
pivots  the  rule  at  (g)  and  at  the  same  time  sighting  the  hill  G,  and  draws  a  line  along 
the  rule  toward  his  body.  Similarly  pivot  the  rule  at  (a),  sighting  A,  and  drawing  a 
line  along  the  rule  toward  his  body  it  cuts  the  line  G  g.  The  intersection  of  the 
lines  at  (f)  is  the  sketcher's  map  location. 

As  the  sketcher  passes  over  the  course  he  should  note  in  writing  on  his  sketch 


20  Military  Sketching  and  Map,  reading 

such  ground  features  as  bridges,  fords,  ferries,  houses,  woods,  cultivated  fields, 
villages,  high  hills,  streams  or  any  other  information  of  importance.     (See  Fig.  8.) 
When  completed  the  following  information  should  be  indicated  at  some  con- 
venient place  on  the  sketch:     (See  Fig.  8.) 

1.  Location  of  sketch. 

2.  Name  and  organization  of  sketcher. 

3.  Date  of  sketch. 

4.  Scale  of  map. 

5.  The  magnetic  north,  and,  if  the  declination  of  the  needle  is  known,  the  true  north 
should  be  indicated  also. 

6.  Reading  scale. 

7.  Contour  interval. 

8.  Scale  of  Map  Distances. 

7  and  8  need  not  be  indicated  unless  the  sketch  is  contoured.     The  subject  of 
contouring  will  be  taken  up  in  a  later  lesson. 


For  Non-commissioned  Officers 


21 


SKETCH  OF  COUNTRY    NORTH-WEST 
OF  GREENVILLE 
By  Sgt.  James  Brown,  Co.  D.  24th  Inf. 


Scale  3  inches  -  I  mile 


V* 


Fig.  8 


22 


MILITARY  SKETCHING  AND  MAP  READING 


16 


1 

\ 
\ 
\ 

/     1 

w              /       * 

\ — w — 

\4. 

B. 


Fig.  9 


FOR  NON-COMMISSIONED  OFFICERS 


23 


24  MILITARY  SKETCHING  AND   MAP  READING 


LESSON  VI 


Conventional  Signs 

Having  learned  how  to  represent  ground  distances  and  directions  on  the  map, 
we  will  now  consider  the  many  natural  and  artificial  ground  features  of  importance 
and  the  method  of  representing  them  on  the  map. 

In  order  that  all  may  be  able  to  read  the  map  when  completed,  we  must  have 
some  fixed  method  of  representing  these  ground  features.  With  this  in  view  the 
United  States  Geographic  Board  adopted,  in  1912,  a  system  of  Conventional  Signs 
for  the  use  of  all  map  making  departments  of  the  government.  At  the  close  of  the 
lesson  are  those  that  pertain  to  the  work  to  be  covered  by  this  book.  Members 
of  the  class  will  be  required  to  reproduce  these  signs  as  neatly  as  possible  and  this 
lesson  will  be  devoted  to  that  purpose. 

The  instructor  should  superintend  and  criticise  the  work,  especially  should  he 
avoid  the  usual  tendency  of  making  the  signs  too  large.  The  ability  to  neatly  repro- 
duce these  conventional  signs  should  be  included  in  the  examination  over  this  sub- 
ject. When  you  find  some  idle  moments  with  pencil  and  paper  at  hand,  your  time 
may  be  profitably  employed  by  practicing  the  construction  of  conventional  signs. 

Just  a  few  words  about  pencils  would  not  be  amiss  at  this  particular  point. 

The  best  for  plotting  are  the  hard  kinds  corresponding  to  Faber's  Siberian 
HHHH  and  HHHHHH,  especially  for  drawing  fine  lines  and  making  points.  For 
most  kinds  of  work,  a  sharp-pointed  pencil  is  used.  For  drawing  long  straight  lines, 
a  chisel-pointed  pencil  should  be  used  to  produce  a  line  of  uniform  breadth.  For 
sketching  and  filling  in  conventional  signs,  softer  pencils  are  preferable,  such  as 
correspond  to  Faber's  HB  or  H.  To  keep  the  point  always  in  good  condition  one 
should  have  a  piece  of  fine  sand-paper  at  hand  for  that  purpose,  being  careful  to 
remove  any  lead  dust  from  the  point  before  using.  Much  more  depends  upon  the 
proper  sharpening  of  a  pencil  and  afterwards  keeping  it  so,  than  is  commonly  sup- 
posed. 

Most  drawings  to  be  inked  are  first  constructed  in  pencil,  the  lines  being  made 
with  as  little  pressure  and  as  fine  as  is  possible  to  show  distinctly. 


For  non-Commissioned  officers 


25 


1 

. 

. 

k 

f           1 

1- 

.    •. 

1 

:: 

| 

4* 

► 

L      >,       < 

! 

;     <U 

y 

1- 

- 

;  t  1 

t-     : 

!! 

i 

■ 

:     E 
2 

j 

* 

- 

" 

to 

1 

i" 

;i 

1 

y 

r 

l-     i- 

*■*- — 

* 

| 

c 

< 

J 

L 

c 

1 

1 

I 

;        1 
1        | 

i      !     3 

■  J'    : 
J  i 

.    *    o    « 

i             « 
!                ] 

o 

i         3 

i 

a 

s 

\ 

i 

1 

* 

| 

a 

5 

L 

ii 

!       * 

* 

■             £ 

*    l    I 

i       1 

I        *          | 

S       w       -5 

c 

.c 
4 

G 
•X 

•fc. 

c 

E 
1 

2 
v. 

•* 

i 

-S 
J 

1  ^ 
^   E 

1?    >< 

• 
I 

< 

1 

E 

I] 
*! 

i 

i 

1  g 

•» 

c 

"1 

c 

L 
C 

C 

<< 

3   - 

«    « 
a    t 

*• 

o 

| 

i 

§  I 

<J 

^ 

«< 

c 

» 

X 

K 

ft: 

fi 

k 

K 

Ul 

26 


MILITARY  SKETCHING  AND  MAP  READING 


si 


e 
I 


1 


E 
I 


1 


r 


«0 

c 

E 
2 


;2 

:  « 

if 

•S 

:.£ 

«! 

rf 

1 

fti 

I 

c  ■ 

o 

it 

1 

1 

c  5 

*: 

tj 

1 

<s 

•4 

■ 

/■ 

+ 

» 
! 

» 

> 

I 

< 

* 
4 

i 

i          : 

* 

■  • 

•     • 

m*» 

10 

p 

« 

■ 

-5 

Ma_ 

8 

1 

». 

m 

* 

* 

^ 

i 

L 

i. 

c 

« 

i 

<: 

5 

• 

I 

g 

;s 

4 

=». 

■ 

i 

4 

jP 

"jj 

i 

>       -5 

c 

• 
1 

■ 

1 

.8 

S 

■ 

<w 

€ 

1 

c 
o 

ID 

• 

I 
•> 

I 

I 

1 

4 

■ 

c 
3 

s 

i 

H 

a 

9 

1 

1 

1 

1 

8 
o 

1 

o 

I 
1 

! 

E 

1 

® 


s 


I 


G 


z 


n 


I 


For  Non-Commissioned  officers 


27 


*•-.* 


#-i  *"■  ^ 

1    4^     *-     ^ 


fl  M 


fci 


*-, 


J 


•I  ">. 


fU 


^77 


§** 


%  ft*. 


8 


£ 


JSSS5 


5Sk 


*..y  ■ 
iSi 


I 


! 


PI 

ill 

! 

i 


I 

■s 


ism 

II .ii'.v  CtatOTlM* 


r 
i 

<0 


I 


V*    "r    ^   'if'*' 

I 


c 


Is 

i 


28 


Military  Sketching  and  Map  reading 


I 

u. 

1 


1 


»"  o'0  o  o  o 

,o°o"0     c°0 
0*°  S."    s  O  o.' 

o  o  0    £ 


'o. 


I 


■yaw 


III 


--v;?,,.; 


I 


::< 


•=-  j.  J-      «-., 


4) 

u 
to 


E 

o 


O    -O.            0    D   ^ 

''>"<>    o 

D         *         $« 

****** 

.»♦»*» 

i       °          *  A 

ai«' 

i?a  e  «•  *  ■* 

*   *    *■   •+- 

+  •*■++) 


a  tjt  ^  '* 

<>  S»  #  £ 

&  a  a  <«• 

'■»  •■>  s»  9 

9  %  o  4 


S 

c 
«l 


a 


"5 
o 


c 
3 


£ 


FOR  NON-COMMISSIONED  OFFICERS 


29 


as. 


OOflOOO  Jl    *flBBBBB 


o      ■• 


s 
f 


i 

E 


f 


I 


-8 
§> 

E 
■a 


5 
1 
3 
| 


I 

•§• 
I 

| 

o 
O 


1 


b 


E 

3 


c 


£    fe 

■s    -a 


-i      o 


I 

u 


«3 


•a 

1 

3 


i 


5  b        H 

3        *        • 


2 

<9 


2 

<« 
o 


I 

<0 


2 

■ 

c 
6 

§      I 
^       -6- 


b 


1 

i 

i  l 

a      E 


Iir.niFF 

"lill  l-.rfll 

iiiSl 

5'ii 
> 

i 

SI 

»  "hi 
m 

30 


MILITARY  SKETCHING  AND   MAP  READING 


c    ■ 


z 

m 

o 

£ 

p 

J 

< 

in 

> 

u 

in 

£E 

J 

m 

m 

< 

re     )S 


o 

I  — 


iS    o 


to 

C  IB 

o 


0    o    ? 
z  z  a 


a.  a.  a  o  cc  a: 


o  s 


3  2 
o  2 


-    o    ? 


O    _     (0     V)     * 

3         ■  ■         fl  Q 

-  *  s  *  * 


■  *  "5 


X   or 


Z  X   Z    c 


Q. 

o 

V) 


.  -J©      g. 

a.  a  a  a    d-  a:  or  a:  «j 


x  X    a        l:  ID 

<  »)  »)  M    5    «  K 


r-'  * 
*  *  * 


O 


no  « 
-o    a  £ 


•    •  < 


r  J5 


rifts! 

<<  <«niiiiaiaiuoooij6au 


o 

*~ 

">      - 

4)                         3 

f"-0       "  u  a 

■»     ID             t     a 

Estu 

Fort. 
Gent 
Gird. 
Grist 

c 

0 

j»  4  * 


T    c 

•  2=6 

•  »      • 


jo  id  a  ■  j)  CJ 


I  S  o  c  1  «•    .  s 

UUUOUOLUUJV 


u-    ©    t>0<£)    .__->   «*    «J 


J3 


<z_    «C    £L 


x?  c  3a  it 


!  '  I 

1  K  2 

3  •■  iS 

I  !  I 

5  o  *} 


&  \ 

3  fc  5 

fe  2  ■ 

2  -S  I. 

c  «  a 

I  §  | 

kl  O  * 


I 


! 


a.       J> 

I       1 

O         °0 


1 


■§ 


I 

I 

8 
3 

1 

•a 

I 

■ 

e 
•c 


] 


c 
u 

E 

i 

c 
2 
c 
Uj 


3 

c 

I      1 
5      I 


\ 

o 
U 


8 

1 

E 


FOR  NON-COMMISSIONED  OFFICERS  31 


LESSON  VII 


Conventional  Signs,  Continued 

Fig.  1 1  represents  the  same  area  as  Fig.  8  in  Lesson  V  except  that  the  natural 
and  artificial  ground  features  have  all  been  represented  by  the  proper  conventional 
signs.  * 

Each  man  will  pass  over  some  designated  course,  plotting  distances  and  direc- 
tions and  sketching  in  all  details  of  military  importance  using  the  conventional  signs 
as  indicated  in  Fig.  11.  A  little  work  of  this  kind  will  greatly  assist  the  student  in 
map  reading.  After  he  has  become  familiar  with  the  conventional  signs,  it  will  be 
found  more  practicable  in  many  cases  in  military  sketching,  especially  in  doing  the 
field  work,  simply  to  write  the  words  in  their  proper  location  as  in  Fig.  8,  rather  than 
to  insert  the  conventional  signs,  while  in  other  cases  it  may  involve  less  labor  to  use 
the  signs,  as  for  example,  streams,  roads,  trails,  bridges,  rail-roads,  buildings,  etc., 
are  much  more  conveniently  represented  by  the  conventional  signs  than  by  any  other 
method,  while  in  the  case  of  woods,  cultivated  fields,  various  classes  of  vegetation 
and  like  details  it  is  without  doubt  much  quicker  and  just  as  accurate  to  write  the 
words:  woods,  corn,  meadow,  etc.,  indicating  their  extent  by  a  light  line  encircling 
the  area. 

In  general,  one  may  follow  the  rule  that  the  best  field  method  to  adopt  is  the 
quickest  and  most  accurate  one  that  will  convey  to  the  mind  of  another  exactly 
what  you  have  observed,  then  if  time  permits  and  conditions  are  suitable  the  sketch 
may  be  traced  representing  all  ground  features  by  the  proper  conventional  signs. 


32 


MILITARY  SKETCHING  AND   MAP  READING 


WEST 


SKETCH   OF  COUNTRY     NOR! 
OF    6REENVILLE 

By  Sgr.  James  Brown.  Co.  D.  24th  Inf. 
Scale   3  inches     '  mile 


Pi*.  11 


FOR  NON-COMMISSIONED  OFFICERS  33 


LESSON  VIII 


Distances  and  Directions,  Continued— Map  Reading 

Having  learned  how  to  represent  ground  distances  and  directions  on  the  map, 
we  should  now  be  able  to  determine  from  the  map  the  distance  between  objects  on  the 
ground  and  the  direction  of  one  from  another. 

We  will  first  consider  converting  map  distance  into  ground  distance.  Every 
complete  map  has  a  reading  scale  of  some  well  known  unit  as  yards  or  miles,  so  all 
that  is  necessary  to  determine  the  ground  distance  between  points  on  the  map  is  to 
apply  the  reading  scale  to  the  map  distance  or  the  map  distance  to  the  reading  scale. 

There  are  several  simple  methods  of  taking  distances  from  the  map: 

1st. — With  the  universal  rule.  If  the  scale  on  the  map  is  one,  two  or  three 
inches  equals  one  mile,  simply  apply  the  universal  rule  and  read  off  the  distance  in 
yards  from  the  corresponding  reading  scales  on  the  rule.  If  the  scale  on  the  map  is 
four,  five,  six  or  any  other  whole  number  of  inches  to  the  mile,  apply  the  reading 
scale,  one  inch  equals  one  mile  and  divide  the  reading  by  four,  five,  six  or  whatever 
the  number  may  be.  Practically  all  military  maps  are  made  on  a  scale  of  a  certain 
whole  number  of  inches  to  the  mile  so  that  the  universal  rule  will  answer  for  scaling 
distances  from  the  map  in  nearly  all  cases.  The  Geological  Survey  Maps  made 
on  a  scale  of  1-62250  are  much  used  by  the  army,  but  as  there  is  a  difference  of  but 
about  one  per  cent  between  these  maps  and  maps  made  on  a  scale  of  one  inch  equals 
one  mile,  (1-63360),  the  one  inch  reading  scale  is  sufficiently  accurate  for  most 
purposes. 

2nd. — Suppose  that  you  have  no  reading  scale  except  the  one  printed  on  the 
map.  If  such  is  the  case,  apply  a  piece  of  straight  edge  paper  to  the  distance  between 
the  two  points  to  be  measured.  Mark  the  distance  on  the  paper  and  apply  the  paper 
to  the  reading  scale  of  the  map,  or  copy  off  the  reading  scale  on  the  edge  of  a  piece 
of  paper  and  apply  the  paper  to  the  map. 

3rd. — A  scale  of  inches  may  be  applied  to  the  distance  between  the  two  points 
to  be  measured,  then  multiply  the  number  of  inches  between  the  points  by  the 
number  of  miles  per  inch  given  on  the  map.  (Caution:  do  not  confusfe  the  terms — 
"miles  per  inch"  and  "inches  per  mile.") 

It  is  often  necessary  to  take  off  distances  from  the  map  in  terms  of  one's  paces. 
To  do  so  simply  apply  your  scale  of  paces  for  one,  three  or  six  inches  eqqals  one  mile 
to  maps  of  those  scales  and  for  maps  of  two,  four,  five  or  any  other  whole  number 
not  represented  on  your  universal  rule,  apply  your  one  inch  scale  of  paces  and  divide 
the  results  by  two,  four  or  five  as  the  case  may  be. 


34  MILITARY  SKETCHING  AND   MAP  READING 

To  Determine  from  the  Map  the  Direction  of  One  Point 

from  Another 

As  the  captain  consults  his  chart  and  compass  in  guiding  his  ship  across  the 
ocean,  so  must  the  soldier  consult  his  map  and  compass  in  traveling  through  unknown 
regions. 

The  usual  style  of  box  compass  or  other  small  compasses  has  the  four  cardinal 
points  N.  E.  S.  and  W.  (North,  East,  South  and  West),  marked  on  its  surface  and 
circle  graduated  in  degrees  reading  zero,  clockwise  around  to  360  degrees,  beginning 
and  ending  at  N.  In  order  to  travel  by  the  compass  one  must  be  able  to  convert 
map  directions  into  compass  directions.  In  other  words  we  must  be  able  to  deter- 
mine the  MAGNETIC  AZIMUTH  of  any  line. 

By  the  MAGNETIC  AZIMUTH  of  a  line  is  meant  the  horizontal  angle  that  the 
line  makes  with  the  compass  needle  measuring  from  the  north  point  clockwise  around 
the  circle.  The  TRUE  AZIMUTH  is  measured  in  the  same  direction  from  the 
north  point  of  the  true  meridian,  (true  north-and-south  line). 

Fig.  12  is  an  illustration  of  a  protractor,  an  instrument  for  measuring  and  plot- 
ting angles.  A  protractor  similar  to  the  one  shown  in  Fig.  12  is  inscribed  on  one  face 
of  the  universal  rule.  This  protractor  is  so  graduated  that  it  is  laid  on  the  east  side 
of  the  meridian  through  the  plotted  position  for  plotting  angles  from  zero  to  180 
degrees;  from  180  degrees  to  360  degrees  the  protractor  is  placed  on  the  west  side 
of  the  meridian. 

To  illustrate, — you  are  at  the  point  A,  Fig.  13.  You  wish  to  obtain  the  magnetic 
azimuth  of  the  line  A  B.  Draw  a  line  A  C,  through  A  parallel  to  the  magnetic  north- 
and-south  line.  Lay  your  protractor  along  A  C,  the  centre  of  the  protractor  at  A. 
(The  center  of  the  protractor  is  indicated  by  the  arrow  point.)  Read  the  number 
of  degrees  between  A  C  and  A  B.  It  is  found  to  be  63  degrees  which  is  the  magnetic 
azimuth  of  the  line  A  B. 

Then  suppose  that  you  are  at  A,  and  wish  to  proceed  in  the  direction  of  B. 
Simply  hold  the  compass  so  that  the  needle  is  at  N.,  then  follow  in  prolongation  of  a 
line  drawn  through  the  pivot  of  the  needle  and  63  degrees.  The  course  is  kept  by 
occasional  reference  to  the  compass  which  is  held  in  front  of  you  or  placed  upon  the 
ground. 

Maps  of  various  scales  should  be  issued  to  each  member  of  the  class  who  should 
determine  the  distances  in  terms  of  yards,  miles  or  his  paces,  and  the  magnetic 
azimuth  between  designated  points  in  accordance  with  instructions  given  in  this 
lesson. 


For  Non-Commissioned  officers 


35 


>\\\\^''tlVlt'l\ll''|l''l|lll 
\<iQ  Ififl  17(1 


--  oo 
-  n  — 
1     -co 


,00 

NO 


—  Cvj 


oo 
~o  CO 


*> 


160 
340 


170 

350 


XRf 


/ 


i   l    ,    ,    I 


ooz 

0? 


061 
01 


36 


MILITARY  SKETCHING  AND   MAP  READING 


'''    I   |    |    /    M  /'''»/    '     I    >    I    I    /    I     I    '  J    T    T    I    T  J 

10  20  / 

ISO  200  .jl'    , 


*A 


« 

I 


Sr 


Fig.  13 


For  Non-Commissioned  Officers  37 


LESSON  IX 


Elevations— Contours — Construction  of  Model  to  Illustrate  Contours 

We  have  learned  how  to  represent  on  the  map  the  horizontal  distance  between 
points  on  the  ground  and  also  the  direction  of  one  point  from  another,  but  in  order 
to  have  a  better  knowledge  of  the  earth's  surface  we  must  devise  some  method  of 
rapidly  determining  elevations.  In  other  words  we  must  know  how  high  the  hills 
are  and  how  deep  the  valleys  are  and  the  extent  of  both. 

This  is  done  by  means  of  CONTOURS,  or  lines  cut  from  the  surface  of  the  earth 
by  imaginary  horizontal  planes  at  equal  intervals  from  each  other. 

The  best  aid  in  studying  the  principles  of  contouring  is  the  sand-table.  Previous 
to  this  lesson  the  artificer  should  construct  a  table  about  six  feet  square  having  a 
cleat  about  four  inches  high  running  around  the  edge,  the  table  to  be  partially  filled 
with  clean  moist  sand. 

In  connection  with  exercises  at  the  sand-table,  the  instructor  should  carefully 
construct  a  model  to  correspond  to  Map  A.  The  model  should  be  constructed  in 
one  corner  of  the  sand-table,  and  should  be  of  the  same  scale  as  Map  A  with  a 
vertical  interval  of  }4  inch  equals  20  feet. 

How  to  Construct  the  Model 

In  one  corner  of  the  table  with  cleats  three  inches  wide,  partition  off  a  rectangle 
22  inches  by  28  inches. 

By  using  tracing  paper  in  connection  with  Map  A,  cut  out  Bristol  board  sheets 
corresponding  to  each  of  the  imaginary  planes.  ' 

Beginning  at  the  datum  plane  (the  table  top)  fill  the  y^  inch  spaces  between 
the  sheets  with  l/2  inch  boards  cut  out  with  a  scroll  saw  to  conform  to  the  horizontal 
planes  cut  from  the  earth.     See  Fig.  14. 

The  step-like  intervals  between  contours  should  be  filled  in  with  putty  and 
smoothed  off  to  correspond  to  the  earth's  surface.     See  Figs.  14  and  15. 

When  the  model  has  hardened,  the  intervals  between  contours  may  be  painted 
green  and  the  edges  of  the  Bristol  board  which  represent  the  contours,  should  be 
traced  with  white  paint,  especially  if  they  have  become  soiled. 

Contour  numbers  and  elevations  of  hill  tops  should  be  indicated  in  white. 

This  model  should  be  carefully  constructed  and  kept  for  reference  during  the 
entire  course.     See  Fig.  15. 

The  following  principles  of  contouring  are  to  be  noted  in  connection  with  the 
model  and  Map  A: 

1.  That  all  points  on  a  contour  line  have  the  same  elevation  above  the  datum 
plane. 


38  MILITARY  SKETCHING  AND   MAP  READING 

2.  That  where  the  contours  are  equally  spaced  the  slope  is  uniform.     (See 

a,  b,  c,  d.) 

3.  That  where  contours  are  straight  and  evenly  spaced,  the  ground  is  a  sloping 

plane.     (See  e,  f,  g,  h.) 

4.  That  the  contours  of  a  vertical  surface  lie  on  top  of  one  another,  as  in  pali- 
sades.    (As  at  H.) 

5.  That  if  the  lean,  in  rocky  formations,  is  over  the  base,  then  only  can  contours 
cross.     (See  x,  y.) 

6.  That  every  contour  closes  upon  itself  or  extends  entirely  across  the  map. 

7.  That  on  water-sheds  the  contours  are  convex  toward  the  base  of  the  slopes. 
(See  i,  j,  k,  1.) 

8.  That  in  water-courses  the  contours  are  convex  toward  the  sources  of  the 
stream.     (See  m,  n,  o,  p.) 

9.  That  contours  far  apart  indicate  gentle  slopes.     (See  q,  r,  s.) 

10.    That  contours  close  together  indicate  steep  slopes.     (See  t,  u,  v.) 
Each  member  of  the  class  should  work  at  the  sand  table  until  he  is  able  to  repre- 
sent each  of  the  typical  forms  indicated  above.     He  will  then  be  required  to  combine 
two  or  more  simpler  forms,  and  finally  he  should  be  able  to  shape  the  sand  into  the 
most  intricate  combinations. 


for  non-Commissioned  officers 


39 


Fig.  14 


Fig.  IS 


40  MILITARY  SKETCHING  AND   MAP  READING 


LESSON  X 


Orientation  and  Map  Reading 

Each  member  being  provided  with  a  map  of  the  surrounding  country,  the  class 
will  now  compare  the  map  with  the  ground  it  represents. 

In  order  to  make  these  comparisons  we  must  first  see  that  the  directions  on  the 
map  and  on  the  ground  coincide.     This  is  called  "ORIENTING"  the  map. 

All  complete  maps  have  both  the  true  and  magnetic  meridian  indicated.  How- 
ever, in  a  previous  lesson  you  found  the  declination  of  the  needle  for  your  particular 
locality,  so  if  either  the  true  or  magnetic  meridian  be  given  the  other  can  readily  be 
determined. 

Methods  of  Orienting  a  Map 

1st  method. — When  the  map  has  a  magnetic  meridian  marked  on  it.  Place  the 
compass  on  the  map,  so  that  the  needle  pivot  rests  on  the  magnetic  meridian,  revolve 
the  map,  until  the  north  end  of  the  needle  and  the  magnetic  meridian  point  in  the 
same  direction,  whereupon  the  map  is  oriented. 

Suppose  that  only  the  true  meridian  is  given  on  the  map.  Knowing  the  decli- 
nation of  the  needle,  construct  a  magnetic  meridian  and  proceed  as  above. 

If  the  magnetic  declination  is  not  more  than  five  degrees,  the  map  can  be  oriented 
nearly  enough  for  map  reading  purposes  by  making  the  compass  needle  coincide  with 
either  meridian. 

2nd  method. — Suppose  that  neither  the  magnetic  nor  true  meridian  is  on  your 
map. 

(a)  Take  a  position  on  the  ground  corresponding  to  some  point  on  the  map. 
Identify  another  place  on  the  map  that  you  can  see  on  the  ground.  Join  the  two 
maps'  positions  by  a  straight  line.  Hold  the  map  so  that  this  line  points  toward 
the  distant  point  seen  on  the  ground  whereupon  the  map  is  oriented. 

(b)  Place  yourself  on  the  line  of  any  two  points  visible  on  the  ground  and  plotted 
on  the  map,  rotate  the  map  until  the  line  joining  the  two  points  on  the  map  points 
toward  the  two  points  on  the  ground,  whereupon  the  map  is  oriented. 

To  locate  one's  position  on  a  map. 

1st. — When  the  map  is  oriented  by  compass. 

Sight  along  the  rule  at  an  object  on  the  ground  at  the  same  time  keeping  the  rule 
on  the  plotted  position  of  this  object  on  the  map.  Draw  a  line  toward  your  body. 
Find  another  point  on  the  ground  that  is  plotted  on  the  map  and  repeat  the  process. 

The  intersection  of  the  two  lines  is  your  map  position.  For  reasons  previously 
explained,  to  obtain  the  best  results  the  two  points  selected  should  be  so  located 


For  Non-Commissioned  officers  4i 

that  the  lines  drawn  will  form  an  angle  not  less  than  30°  nor  greater  than  150°.  (See 
Fig.  10,  Lesson  V.) 

2nd. — If  the  map  has  been  oriented  by  means  of  a  straight  line  drawn  between 
two  map  points,  then  it  will  be  necessary  to  draw  but  one  line  from  an  object  on  the 
ground,  and  the  intersection  of  this  line  with  the  line  already  on  the  map  will  be 
your  location  on  the  map. 

Having  oriented  the  map  and  located  your  position  on  it,  you  should  proceed 
along  the  roads  and  trails,  keeping  the  map  constantly  oriented  and  comparing 
ground  features  with  map  features. 

If  you  lose  your  position,  verify  it  by  one  of  the  methods  given  above,  or  by 
estimating  the  map  distance  you  should  have  traveled  in  a  known  time,  or  by  actually 
pacing  the  course. 

After  each  member  of  the  class  has  learned  to  orient  the  map  and  to  locate 
his  position  on  the  maps  by  all  of  the  methods  explained  above,  the  instructor  should 
accompany  the  class  over  some  course  comparing  all  ground  and  map  features. 


42  MILITARY  SKETCHING  AND   MAP  READING 


LESSONS  XI  AND  XII 


The  Game  of  "Hide  and  Seek" 

■ 

Two  members  of  the  class  are  selected  to  choose  sides.  One  side  is  called  the 
"Hiders,"  the  other  side,  the  "Seekers."  All  are  provided  with  maps  covering  the 
area  over  which  the  game  is  to  be  played.  This  area  should  include  at  least  four 
square  miles,  preferably  of  rolling  country  possessing  few  roads  or  trails  and  a 
considerable  amount  of  vegetation. 

The  instructor  then  separates  the  "Hiders"  from  the  "Seekers."  Each  "Hider" 
receives  written  instructions  as  to  the  location  of  his  hiding  place.  The  "Hider"  will 
not  be  permitted  to  enter  any  enclosure,  but  will  go,  as  nearly  as  he  can  estimate 
to  the  spot  designated  in  his  instructions,  and  by  sitting  or  lying  down  conceal  him- 
self so  that  he  cannot  be  seen  at  a  distance  greater  than  100  yards. 

The  written  instructions  may  read  something  like  the  following: 

Sergt.  Jones: 

You  will  go  to  the  point  marked  "A"  on  your  map,  and 
conceal  yourself  there  as  explained  heretofore,  and  await  further 
instructions  from  me. 

(Sgd.)     J.  M.  SMITH, 
Capt.,  24th  Infty. 

Each  "Hider"  will  be  equipped  with  map,  compass,  universal  rule,  pencil,  eraser 
and  pocket  knife. 

Before  starting  out  each  "Hider"  must  locate  his  present  position  on  the  map, 
he  must  determine  the  magnetic  azimuth  of  A  and  the  distance  from  his  present 
position  to  A  in  terms  of  his  paces.  If  there  is  some  obstacle  in  the  way  so  that 
he  cannot  take  a  direct  course,  he  should  select  some  other  indirect  course  and  deter- 
mine the  distances  and  azimuths  of  the  various  lines  of  the  course  selected.  For 
example,  suppose  that  he  is  at  P  and  is  directed  to  proceed  to  A,  Fig.  16.  He  is  unable 
to  cross  Green  River  except  by  the  bridge  at  B,  therefore  he  cannot  take  the  direct 
course  P  A,  but  must  go  along  the  road  P  B,  until  he  crosses  the  bridge  and  then 
proceed  directly  to  A  from  B.  In  this  case  he  would  proceed  to  the  bridge — then 
determine  from  his  map  the  distance  B  A  in  terms  of  his  paces  and  the  magnetic 
azimuth  of  B  A.  If  he  has  mastered  the  previous  lessons  he  should  be  able  to  figure 
this  all  out  for  himself. 

After  a  sufficient  prescribed  time  has  elapsed  each  "Seeker,"  (up  to  this  time 
the  "Seekers"  have  been  unable  to  watch  the  proceedings  of  the  "Hiders"),  will  be 
given  instructions  corresponding  to  some  one  of  the  "Hiders,"  and  he  will  attempt 
to  locate  his  "Hider"  as  soon  as  possible. 

After  due  time  has  elapsed  (the  time  being  previously  arranged)  the  instructor 


for  Non-Commissioned  Officers  43 

will  have  "Recall"  sounded.  At  the  sounding  of  "Recall"  all  "Hiders"  and 
"Seekers"  will  remain  in  place  standing. 

The  instructor  will  then  verify  positions.  The  "Seekers"  score  will  be  computed 
as  follows: 

For  each  "Hider"  who  was  not  hidden  within  100  yards  of  his  designated  hiding 
place,  the  "Seekers"  gain  one  point;  they  also  gain  one  point  for  each  correctly 
located  "Hider"  that  is  found  by  the  corresponding  "Seeker."  The  instructor's 
decision  as  to  whether  the  "Hider"  is  properly  located  will  be  final. 

The  following  day  the  "Seekers"  will  become  the  "Hiders"  and  vice  versa. 
New  hiding  places  will  be  designated  and  the  proceedings  of  the  previous  day  re- 
peated.    The  side  having  gained  the  greatest  number  of  points  of  course  wins. 

This  game  may  be  played  between  Sergeants  and  Corporals,  or  in  any  other 
way  to  insure  the  greatest  competition.  Certain  privileges  may  also  be  granted  to 
the  winning  team. 


44 


Military  Sketching  and  Map  Reading 


1 


i 


Scale    3    =  1  mile 
v.  •/»       


I  mill 


Fijr     16 


FOR  NON-COMMISSIONED   OFFICERS  45 


LESSON  XIII 


Measurement  of  Angles  of  Slopes — Construction  of  Slope  Board 

— Scale  of  Map  Distances 

From  the  model  constructed  in  a  previous  lesson  in  connection  with  Map  A, 
and  work  at  the  sand-table,  the  student  should  now  understand  what  contour  lines 
are,  and  the  necessity  of  placing  contour  lines  on  maps  in  order  to  form  a  correct  idea 
of  the  locations  and  extent  of  the  elevations  and  depressions  of  the  earth's  surface. 

The  surface  of  the  ground  is  either  level  or  sloping.  As  one  walks  along  a  level 
course  his  elevation  naturally  remains  the  same,  while,  if  he  walks  along  a  sloping 
course,  his  elevation  increases  or  decreases  according  as  he  is  going  up  or  down  hill. 

It  has  been  found  that  the  up  hill  end  of  a  line  57.3  feet  long  which  has  a  slope 
of  one  degree  is  one  foot  higher  than  the  down  hill  end.  Computing  from  these 
figures  we  are  able  to  determine  the  difference  of  elevation  between  any  two  points 
if  we  know  the  distance  and  the  angle  of  slope  between  the  points.  The  distance  may 
be  determined  by  pacing,  intersection,  resection,  etc.,  and  the  angle  of  slope  by 
various  instruments  especially  prepared  for  that  purpose  most  of  which  are  rather 
expensive  and  quite  apt  to  get  out  of  adjustment. 

The  most  practicable  method  of  ascertaining  angles  of  slopes  is  by  means  of  the 
slope-board  which  is  inexpensive,  easy  of  construction  and  never  gets  out  of  adjust- 
ment. 

Method  of  Construction 

On  your  drawing-board  (see  Fig.  17)  construct  D  C  perpendicular  to  A  B,  then 
when  a  point  is  sighted  along  the  straight  edge  A  B,  the  plumb  line  attached  at  D 
makes  the  same  angle  with  the  perpendicular  D  C  that  A  B  makes  with  the  hori- 
zontal. 

Lay  off  D  E,  5.73  inches  long  on  D  C,  then  with  the  radius  D  E  describe  the 
semi-circle  F  E  G.  Lay  off  from  E  toward  F  and  G  successive  distances  of  l-10th 
inch  along  the  arc.  These  divisions  represent  degrees,  because  one  degree  in  a 
circle  of  5.73  inches  radius  gives  a  cord  of  1-lOth  inch.  Extend  these  degree  marks 
to  the  foot  of  the  board  with  a  ruler  as  shown  in  Fig.  17. 

To  read  slopes,  attach  a  plumb  line  at  D,  sight  along  A  B  at  the  object,  keeping 
the  board  in  a  vertical  plane.  When  the  plumb  line  comes  to  rest,  press  the  string 
against  the  edge,  of  the  board  with  the  fingers  and  read  the  angle  marked. 

Having  a  drawing-board  equipped  with  the  device  for  reading  angles  of  slope, 
a  scale  of  M.D.'s  (map  distances  between  contours),  will  now  be  explained.  Such 
a  scale  will  be  found  on  the  Universal  Rule  for  Military  Sketching  and  Map  Reading. 


46  Military  Sketching  and  map  Reading 

Scales  of  Map  Distances  may  also  be  obtained  from  the  Secretary,  Army  Service 
Schools,  Fort  Leavenworth,  Kansas. 

A  Normal  System  of  Scales  has  been  prescribed  for  TJ.  S.  Army  field  sketches 
as  follows: 

Sketches  of  large  areas 1  inch     =  1  mile,  V.I.,  60  feet. 

Road  sketches , 3  inches  =  1  mile,  V.I.,  20  feet. 

Position  sketches 6  inches  =  1  mile,  V.I.,  10  feet. 

Fortification  sketches 12  inches  =  1  mile,  V.I.,    5  feet. 

It  will  be  seen  that  as  the  scale  is  increased  the  vertical  interval  between  contours 
is  proportionally  decreased,  so  that  by  this  system  the  M.D.  is  always  the  same  for 
the  same  angle  of  slope  whatever  the  scale  of  the  map  may  be. 

The  M.D.  for  any  angle  of  slope  may  be  computed  from  the  following  equation: 

-r — -. — -?—. — —  =M.D.  in  which  688  equal  the  horizontal  distance  in  inches  on  a 
Angle  of  slope 

one  degree  slope  necessary  to  give  a  rise  of  one  foot.     The  V.I.  is  expressed  in  terms 

of  feet. 

If  the  R.F.  and  V.I.  for  any  sketch  made  in  accordance  with  the  Normal  System 

be  substituted  in  the  above  equation  the  M.D.  will  be  the  same  for  any  particular 

angle.     In  view  of  this  let  us  substitute  R.F.  =1-63360  and  V.I.  =60,  and  let  the 

688  x      1      X.60 

angle  of  slope  be  one  degree,  and  we  have - =.65  inch  (the  M.D.  for 

one  degree  slope  for  any  sketch  under  the  Normal  System.) 

Dividing  .65  by  %,  }4,  $4,  1,  2,  3,  4,  etc.,  we  have  the  M.  D.  for  %,  yi  degrees 
etc.,  as  shown  on  the  Universal  Rule. 

Maps  with  R.F.  and  V.I.  corresponding  to  the  Normal  System  should  be  issued 

to  the  class,  and  each  man  should  determine  angles  of  slope  between  contours  on  the 

maps.     In  this  connection  the  following  table  of  practicability  of  slopes  should  be 

studied: 

Degrees  of 

slope  Operations. 


1 

3 

5 


7 
8 

14  to  15 
18H 


Maximum  for  railroads. 

Maximum  for  first-class  roads. 

Practicable  for  all  arms.    Somewhat  difficult  for 

cavalry  to  charge  descending. 
Maximum  for  cavalry  charge  in  mass  ascending. 

Infantry  in  close  order  descends  with  some 

difficulty. 
Cavalry  can  descend  at  a  trot. 
Not  practicable  for  heavy  loaded  vehicles. 
Field  artillery  can  no  longer  maneuver. 
Maximum  up  to  which  all  arms  can  move. 
Light  vehicles  can  ascend. 


26  Foot  troops  can  ascend  or  descend  aided  by  hands. 


FOR  NON-COMMISSIONED  OFFICERS 


47 


s^a  T 


F^44i, 


UuSu*^6 


//i/iliiiihuili 


S         lp    o 


Fig.  17 


48  MILITARY  SKETCHING  AND   MAP  READING 


LESSON  XIV 


Profile  Method  of  Spacing  Contours 

Having  constructed  our  slope  board  and  scale  of  map  distances  for  slopes  we 
will  now  determine  the  methods  in  detail  of  finding  the  elevation  of  an  unknown 
point  D,  from  a  known  point  A,  and  the  location  of  contours  on  this  line. 

A  D  is  the  road  to  be  contoured.  Draw  several  lines  parallel  to  A.D.  with  a 
vertical  interval  of  1-20  inch. 

.  A  b  c  d  is  a  profile  of  the  road,  vertical  scale  1-20  inch  equals  20  feet. 

A  profile  is  a  line  supposed  to  be  cut  from  the  surface  of  the  earth  by  an  imaginary 
vertical  plane.  , 

It  is  customary  to  draw  a  profile  with  a  greater  vertical  than  horizontal  scale 
in  order  that  the  slopes  of  the  hills  may  appear  more  clearly  to  the  eye. 

Glancing  at  the  profile  of  the  road  A  D,  we  find  conspicuous  points  of  elevation 
or  depression  as  b  c  and  d,  these  are  called  CRITICAL  POINTS,  or  points  where 
there  are  abrupt  changes  of  general  slope.  It  is  seldom  the  case  that  a  slope  is  uni- 
form. There  are  constant  slight  changes  of  slope  (see  Fig.  18,  A  to  b)  and  occasionally 
a  decided  change  as  at  b  c  and  d.  If  we  should  attempt  to  ascertain  every  change 
of  slope,  it  would  be  an  endless  and  confusing  task,  and  our  error  would  constantly 
be  multiplying.  Instead,  we  start  at  A  which  is  known  to  be  900  feet  above  sea 
level.  We  glance  along  the  road  ahead  of  us  and  see  numerous  slight  changes  of 
slope,  and  finally  at  b  is  a  hill  top  that  stands  out  conspicuously.  With  the  slope 
board  we  sight  at  b  and  find  the  angle  of  slope  to  be  3>^  degrees. 

We  now  pace  from  A  to  b  and  lay  off  the  distance  A  B.  (All  road  sketches, 
as  stated  before,  are  drawn  to  a  scale  of  3  inches  equals  1  mile  and  a  V.I.  of  20  feet.) 

Applying  our  scale  of  Map  Distances  for  3>y2  degrees  to  A  B,  we  find  that  it  is 
contained  \l/2  times. 

Multiply  20  feet  (the  contour  interval)  by  4>^  and  we  find  that  the  elevation 
of  b  is  990  feet. 

At  B  erect  the  perpendicular  Bb  A.]/2  of  the  1-20  inch  spaces  in  height,  each 
space  representing  20  feet.     Mark  b,  990  feet. 

Now  from  the  hill,  b,  glance  backward  at  A  and  plot  the  profile  Ab  as  the  road 
actually  appears  to  you.  Where  this  profile  intersects  the  horizontal  lines  drop 
perpendiculars  to  the  line  A  E  which  represents  your  road.  By  this  method  you 
have  the  elevations  of  the  critical  points  determined  very  accurately  and  the  inter- 
vening contours  spaced  correctly  enough  to  give  a  very  good  idea  of  the  slopes. 

Having  located  the  contours  on  the  road  between  A  and  B,  extend  each  contour 
to  the  right  and  left  of  the  road  as  far  as  you  can  see  plainly,  so  as  to  represent  the 
true  conformation  of  the  ground  (see  Fig.  18.) 

From  b  sight  at  the  next  critical  point,  c.     You  find  that  the  angle  of  elevation 


FOR  NON-COMMISSIONED  OFFICERS        '  49 

is  two  degrees.  Pace  b  c  and  lay  off  the  distance  B  C.  Apply  your  scale  of  map 
distances.    It  is  contained  i%  times.    4>^+3^  =8>^. 

At  C  erect  a  perpendicular  %%  spaces  high  and  mark  elevation  of  c,  900+ 
(8#  X20)  or  1065  feet. 

From  c,  plot  the  profile  of  the  road,  c  b  as  it  actually  appears  to  you,  and  where 
the  profile  intersects  the  horizontal  lines  drop  perpendiculars  to  the  line  B  C,  thus 
locating  your  contours  between  B  and  C. 

Proceeding  in  the  same  manner  from  c  to  d,  you  find  an  angle  of  4  degrees 
"depression."  Pace  c  d,  and  lay  off  the  distance  C  D.  Applying  your  scale  of  map 
distances  to  C  D  you  find  that  it  is  contained  5>2  times.  S% — ^A  =2^  or  d  is  2^ 
spaces  above  the  datum  plane,  or  has  an  elevation  of  900  +  (2f£  x20)  =955  feet. 

After  a  most  careful  explanation  of  the  above  method  of  contouring,  the  instructor 
should  issue  profile  paper  to  each  member  of  the  class.  He  should  then  indicate 
distances  and  slopes  between  imaginary  critical  points,  and  the  members  of  the  class 
will  lay  off  the  distances,  using  any  one  of  the  Normal  Scales,  apply  their  M.D. 
(map  distance)  scale  and  erect  perpendiculars  at  the  critical  points,  indicating  their 
elevations.  They  will  then  draw  in  any  imaginary  profile  of  the  road  between  critical 
points  and  drop  perpendiculars  from  the  intersection  of  the  profile  with  the  horizontal 
planes. 

For  slopes  of  less  than  five  degrees,  the  vertical  scale  of  the  profile  should  be 
reduced  to  1-10  inch. 

The  next  two  lessons  will  involve  the  actual  field  work,  employing  the  principles 
taught  in  this  lesson. 

We  must  learn  to  creep  before  we  walk,  and  it  is  believed  that  after  two  days 
practice  in  contouring  with  the  aid  of  the  profile  method  that  the  student  will  be 
able  to  space  the  contours  between  critical  points  without  using  the  profile  paper. 


50 


MILITARY  SKETCHING  AND  MAP  READING 


Fig.  19 


FOR  NON-COMMISSIONED  OFFICERS  51 


LESSONS  XV,  XVI  AND  XVII 


Contouring  (Continued) 

The  instructor  should  select  a  road  of  course  two  or  three  miles  long  possessing 
a  few  well  defined  critical  points^ 

Each  sketcher  should  be  equipped  with  a  drawing-board  with  compass  and  the 
attachment  for  reading  slopes,  the  Universal  Rule,  a  hard  well-sharpened  pencil, 
knife  and  eraser,  also  profile  paper,  with  either  1-10  inch  intervals  or  1-20  inch  inter- 
vals.   If  the  course  is  rugged  use  the  1-20  inch  profile,  otherwise  the  1-10  inch  profile. 

The  instructor  should  emphasize  the  importance  of  using  hard  pencils  and  keep- 
ing them  well-sharpened  for  this  work.  He  should  also  accompany  the  sketchers, 
constructing  the  profile  and  contours  of  the  road. 

When  the  work  has  been  completed  the  class  should  be  assembled,  results 
compared  and  errors  pointed  out. 

Lessons  XV  and  XVI  are  devoted  to  this  method  of  contouring  after  which 
it  is  believed  that  the  sketcher's  eye  will  be  trained  so  as  to  enable  him  space  the 
contours  between  critical  points  with  a  fair  degree  of  accuracy. 

For  Lesson  XVII  the  instructor  should  indicate  a  course  about  three  miles  long 
as  in  the  above  lessons,  but  the  contours  between  critical  points  are  to  be  drawn 
in  without  the  aid  of  the  profile  paper. 

After  each  lesson  the  class  should  be  assembled  and  results  compared. 


52  MILITARY  SKETCHING  AND   MAP  READING 


LESSONS  XVIII  AND  XIX 


The  Road  Sketch  Complete 

We  have  learned  how  to  plot  on  the  map  ground  distances,  directions,  elevations, 
and  the  various  natural  and  artificial  ground  features  of  military  importance. 

We  will  now  make  a  complete  road  sketch.  The  instructor  will  designate  some 
road,  say,  three  or  four  miles  long.  Each  member  of  the  class  will  go  over  the  desig- 
nated road,  plotting  distances,  directions,  elevations  and  important  ground  features 
as  outlined  in  previous  lessons. 

The  sketch  should  not  only  include  the  road  itself  but  an  area  extending  400 
yards  each  side  of  the  road.  As  a  rule  most  of  this  area  can  be  seen  from  high 
elevations  along  the  road-bed,  but  occasionally  it  may  become  necessary  to  go  to  an 
elevated  point  outside  of  the  road  to  secure  all  of  the  details.  Important  objects 
such  as  high  hills,  towns,  etc.,  which  are  more  than  400  yards  from  road-bed  should 
be  located  by  intersection.  When  hills  have  been  located  by  intersection  their 
elevations  should  be  determined  by  applying  the  Scale  of  Map  Distances  and  the 
elevations  noted  on  the  sketch. 

The  most  practicable  method  of  indicating  details  on  maps  or  sketches  made 
in  the  field  is  shown  in  Fig.  19.  Vegetation,  fences,  etc.,  should  be  indicated  by  words 
rather  than  by  the  proper  conventional  signs.  In  short  the  best  field  method  is 
the  quickest  and  most  accurate  method.  For  more  elaborate  map  work  the  author- 
ized conventional  signs  may  be  used  as  shown  in  Fig.  20. 

In  order  that  the  student  may  become  familiar  with  all  of  the  conventional 
signs  which  is  very  important  when  it  comes  to  map  reading,  the  field  sketches  may 
be  retouched  at  leisure  employing  the  proper  conventional  signs  in  each  case,  as 
shown  in  Figs.  19  and  20. 

The  beginner  should  sketch  in  every  feature  of  military  importance,  so  as  to 
become  familiar  with  the  Conventional  Signs  and  to  train  the  eye  to  observe  details. 
Later,  he  may  be  called  upon  to  submit  sketches  showing  only  such  information 
as  might  be  required  for  particular  expeditions. 

At  the  close  of  the  lesson  the  instructor  will  collect  the  sketches,  and  before 
the  next  lesson  he  will  note  on  each  sketch  all  the  glaring  defects. 

At  the  beginning  of  Lesson  XIX  the  sketches  will  be  returned,  errors  and  omis- 
sions pointed  out,  and  a  new  road  of  about  the  same  length  as  the  one  in  the  previous 
lesson  will  be  designated,  so  that  Lesson  XIX  will  be  the  same  as  Lesson  XVIII, 
except  that  the  sketcher  will  be  in  a  position  to  profit  by  the  experience  of  the  last 
lesson. 


For  Non-Commissioned  Officers  53 

A  Few  Rules  to  be  Observed 

1.  The  beginner  should  never  attempt  to  hurry,  even  if  he  is  unable  to  complete 
the  task  assigned  to  him. 

2.  Devote  equal  time  and  care  to  all  parts  of  the  sketch. 

3.  Be  sure  that  your  orientations  are  correct  and  that  your  board  is  kept 
oriented. 

4.  Do  not  leave  a  station  or  critical  point  until  all  of  the  details  up  to  that 
point  have  been  put  in. 

5.  Do  not  attempt  to  show  too  minute  details.  You  must  get  the  distances, 
directions,  elevations  of  critical  points,  and  by  intersection  locate  only  such  land- 
marks as  may  assist  you  in  identifying  your  location  later,  or  that  are  of  military 
importance,  such  as  high  hills,  towns,  etc.  By  close  observation  and  taking  a  few 
notes  as  you  pass  along  the  road,  the  remaining  details  such  as  fences,  cultivated 
fields,  buildings,  cuts  and  fills,  bridges,  railroad  crossings,  telegraph  lines,  etc.,  may 
be  filled  in  from  the  critical  points.  , 

6.  Be  sure  that  the  drainage  has  been  properly  outlined  before  attempting  to 
extend  the  contour  lines  each  side  of  the  road,  in  other  words,  first  locate  conspicuous 
hill  tops  and  the  course  of  stream  beds  and  valleys.  This  is  most  important,  as 
extending  contour  lines  without  first  indicating  what  we  may  call  the  frame-work  of 
the  drainage  would  be  like  fitting  a  garment  without  trying  it  on  or  without  making 
previous  measurements. 

7.  To  become  a  rapid  and  an  accurate  sketcher  one  must  be  able  to  estimate 
distances  with  less  than  ten  per  cent  error  up  to  600  yards  and  within  fifteen  per  cent 
up  to  a  mile.  Estimates  of  distances  should  be  made  in  yards  and  the  ground  distance 
and  map  distance  for  100  yards  should  be  distinctly  fixed  in  the  mind  as  reference 
units.     (See  Estimating  Distance  Firing  Regulations,  U.  S.  Army.) 


54 


Military  Sketching  and  Map  Reading 


ROAD   A.B.C.D. 

Scale     3  m  =»  I   mil© 
V  I    20  Feet 


giUof  Suit 


Fig.  19 


Scjlt  *f  Map  Ditlinces 


FOR  NON-COMMISSIONED  OFFICERS 


55 


Racing  StaU 


«•         a*       4»      i« 


Seal*  «f   Map  DUUikm 


Fig.  20 


56  Military  sketching  and  Map  reading 


LESSON  XX 


Position  Sketch 

Military  sketches  may  be  classified  as  "Road  Sketches"  and  "Area  Sketches." 
We  have  already  discussed  the  Road  Sketch  in  Lessons  XVIII  and  XIX.  Area 
Sketches  are  classified  as: 

1st.  The  Position  Sketch,  in  which  military  conditions  are  such  that  the  sketcher 
is  at  liberty  to  visit  any  part  of  the  area  to  be  sketched. 

2nd.  The  Outpost  Sketch  in  which  the  sketcher  is  usually  able  to  visit  only  that  part 
of  the  area  in  rear  of  his  own  line  of  observations. 

3rd.    The  Place  Sketch,  which  is  made  by  the  sketcher  from  one  point  of  observation. 

In  this  lesson  we  will  consider  only  the  Position  Sketch.  The  scale  of  this  sketch 
is  six  inches  equals  one  mile  with  a  contour  interval  (V.I.)  of  ten  feet. 

For  the  beginner,  the  work  involved  in  making  a  position  sketch  is  divided  into 
two  parts: 


1st.      The  Frame-work. 
2nd.     Filling  in  details. 


The  Frame- Work 


To  illustrate,  you  are  required  to  make  a  Position  Sketch  covering  an  area  of 
one  square  mile.  The  construction  of  the  frame-work  (that  is  the  location  of  a 
sufficient  number  of  critical  points  as  will  enable  the  sketcher  to  fill  in  all  details  of 
military  importance),  is  divided  into  three  distinct  parts: 

1st.      Select  and  measure  a  Base  Line. 

2nd.    Location  of  Critical  Points  by  Intersection. 

3rd.     Location  of  Points  by  Resection. 

The  Base  Line 

The  base  line  should  be  about  one-third  as  long  as  the  greatest  dimension  of  the 
area  to  be  sketched.  (See  A  B,  Fig.  21)  and  should  be  as  centrally  located  as  possible. 
Its  ends  should  be  marked  by  some  conspicuous  natural  objects.  If  this  is  not 
practicable,  poles  with  white  banners  should  be  placed  at  the  ends,  or  any  other 
method  by  means  of  which  these  points  may  be  seen  from  a  distance.  The  base 
line  should  be  on  as  level  ground  as  practicable  with  a  good  view  over  the  ground  to 
be  mapped.  If  the  country  is  hilly  a  good  base  can  usually  be  established  along 
some  ridge. 


FOR  NON-COMMISSIONED  OFFICERS  57 

Intersection  and  Resection 

Suppose  that  we  have  selected  the  base  line  A  B,  Fig.  21.  From  the  extremities 
and  known  points  on  this  base  line  the  points  (indicated  by  letters  C  D  E  F  G  H  I, 
Fig.  21)  may  be  located  by  intersection  as  explained  in  Lesson  V.  Any  other  required 
points  throughout  the  area  (indicated  by  figures  1,  2,  3,  4,  5,  6,  7  and  8,  Fig.  21)  may 
be  located  by  resection  as  explained  in  the  same  lesson. 

Points  located  on  the  sketch  by  intersection  and  resection  should  be  such  as  will 
outline  the  drainage  system,  as,  for  example,  conspicuous  hill  tops,  bridges  and 
important  bends  in  the  course  of  streams,  the  junction  of  streams  and  deep  valleys, 
etc.,  also  any  other  points  that  will  assist  in  making  a  frame-work  for  the  sketch  or  in 
locating  the  sketcher's  position. 

Filling  in  Details 

Angles  of  elevation  or  depression  between  points  located  by  intersection  or 
resection  will  be  measured,  the  M.D.  scale  applied  to  the  lines  connecting  these  points 
and  their  elevations  noted  on  the  sketch.  Then  with  the  drainage  system  outlined, 
and  the  elevations  of  many  points  known,  the  sketcher  should  experience  no  difficulty 
in  drawing  in  the  contours  by  eye. 

Other  details  such  as  the  vegetation,  buildings,  bridges,  cuts,  fills,  fords,  ferries, 
roads  and  trails,  etc.,  may  be  sketched  in  from  points  located  by  intersection  and 
resection. 

Bear  in  mind  the  importance  of  outlining  the  drainage  before  drawing  in  any 
contours. 

Fig.  22  includes  the  same  area  as  Fig.  21,  with  the  details  sketched  in. 

After  the  instructor  has  thoroughly  explained  the  subject  of  BASE  LINES, 
INTERSECTION  AND  RESECTION,  he  will  take  the  class  to  some  large  room 
in  barracks,  and  locate  all  of  the  main  features  of  the  room  by  establishing  a  base 
line  on  a  conveniently  large  scale,  say  1-40,  and  locating  points  by  intersection  and 
resection.  He  should  assure  himself  that  each  member  of  the  class  understands 
the  principles  involved  in  making  a  Position  Sketch,  as  in  the  following  lesson  they 
will  be  required  to  actually  perform  the  work  in  the  field. 


58 


MILITARY  SKETCHING  AND  MAP  READING 


FRAME  WORK 

POSITION    SKETCH. 

Jca/e  S"*  I  mile 


A.  B.   is  the  Base    Line 
C.  D.  £..  F.  G.  H.  I.    Points  located  try  intersection 
1. 2.3. 4.5. 6. 7.6    Points  located  by  resection 
Intersection  lines  are  plain* 
tfesec/fon  lines  are  broken. 


Fig.  21 


FOR  NON-COMMISSIONED  OFFICERS 


59 


POSITION     SKETCH 

Jones  Cr.  and  Black  River. 


■Scale  6  'ilmi 


Fig.  22 


60  Military  Sketching  and  map  Reading 


LESSONS  XXI,  XXII  AND  XXIII 


Position  Sketch  (Continued) 

The  instructor  should  designate  a  certain  area  of  about  one  square  mile  to  be 
sketched,  and  will  go  over  the  ground  selected  with  the  class  and  choose  a  suitable 
base  line  as  described  in  the  previous  lesson. 

After  the  base  line  has  been  decided  upon  each  member  of  the  class  will  proceed 
to  construct  the  frame-work  of  the  sketch  by  measuring  and  laying  off  the  base  line 
and  locating  points  by  intersection  and  resection.  Perhaps  no  two  men  will  select 
the  same  critical  points  throughout  the  entire  framework.     This  does  not  matter. 

In  constructing  the  frame-work  of  a  position  sketch,  the  following  points  should 
be  remembered: 

1.  Exercise  great  care  in  pacing  and  laying  off  the  base  line. 

2.  See  that  the  directions  of  the  base  line  and  magnetic  meridian  as  plotted 
on  your  sketch  correspond  exactly  with  the  direction  of  the  base  line  and  the  compass 
needle. 

3.  In  locating  points  by  intersection  and  resection,  see  that  your  drawing- 
board  is  exactly  oriented.  Pivot  your  ruler  carefully,  and  sight  accurately  at  the 
ground  objects.     Use  a  hard  well-sharpened  pencil. 

The  class  will  be  instructed  to  locate  a  certain  number  of  points  by  intersection 
and  a  certain  number  by  resection.  When  this  has  been  accomplished,  results  will 
be  compared  and  errors  pointed  out.  The  work  should  be  criticized  by  the  instructor 
before  leaving  the  area  sketched. 

Lesson  XXII  will  be  devoted  to  filling  in  details  as  shown  in  Fig.  22,  Lesson  XX. 

For  Lesson  XXIII  a  certain  area  will  be  designated  by  the  instructor  but  the 
men  will  select  their  own  base  lines,  and  details  will  be  filled  in  as  the  frame-work 
progresses. 


FOR  NON-COMMISSIONED  OFFICERS  61 


LESSONS  XXIV  AND  XXV 


The  Outpost  Sketch 

The  same  methods,  scale,  and  V.I.  are  employed  in  making  an  outpost  sketch 
as  are  used  with  the  position  sketch  with  the  one  exception,  that,  in  the  former  case 
the  sketcher  is  unable  to  visit  that  portion  of  the  area  to  be  mapped  beyond  the  line 
of  observation. 

The  location  of  the  base  line  will  depend  upon  the  nature  of  the  ground  and 
whether  or  not  the  sketcher  is  under  fire.  In  some  cases  it  may  be  located  along  the 
line  of  observation,  and  points  to  the  front  located  by  intersection  or  estimation. 
When  under  fire  it  would  be  necessary  to  locate  the  base  some  distance  in  rear  of  the 
line  of  observation,  locating  points  between  the  base  and  the  line  of  observation  by 
either  intersection  or  resection,  and  points  beyond  the  line  of  observation  by  inter- 
section or  estimation.  Several  critical  points  should  always  be  located  along  the 
line  of  observation,  the  sketcher  approaching  these  points  by  creeping  up  from  the 
rear,  orienting  his  board  flat  on  the  ground,  and  sighting  necessary  critical  points 
over  the  foreground. 

The  non-commissioned  officer  in  time  of  war  will  frequently  be  called  upon  to 
make  a  sketch  of  that  portion  of  the  outpost  including  one  support,  its  outguard, 
line  of  observation,  etc.,  and  if  he  hopes  to  be  really  efficient  and  render  his  country 
the  greatest  service  possible  in  time  of  need,  he  should  exercise  the  greatest  pains 
in  mastering  this  lesson  in  connection  with  paragraphs  123  to  141  inclusive,  Field 
Service  Regulations,  1913,  which  will  give  him  a  very  good  idea  of  the  features  to  be 
noted  on  the  sketch. 

Field  glasses  will  be  found  very  useful  in  studying  the  foreground,  thus  showing 
up  many  folds  of  the  ground  not  visible  to  the  naked  eye.  The  ground  must  be  shown 
from  one-half  to  two  miles  in  front  of  the  line  of  observation,  this  of  course  depending 
upon  the  nature  of  the  country. 

The  instructor,  after  explaining  the  preceding  portion  of  this  lesson,  should 
march  his  company  or  troop  to  suitable  grounds,  establish  an  outpost,  and  require 
each  non-commissioned  officer  to  submit  a  sketch,  showing  all  the  ground  features, 
locations  of  support,  outguards,  and  sentinels,  lines  of  retreat,  and  in  fact  every 
detail  of  military  importance  that  the  commander  of  the  outpost  should  know. 
Sketches  to  be  submitted  and  errors  pointed  out  before  the  outpost  is  relieved. 

The  operation  will  be  repeated  in  Lesson  XXV,  a  new  location  for  the  outpost 
being  selected. 


62  MILITARY  SKETCHING  AND   MAP  READING 


LESSONS  XXVI  AND  XXVII 


The  Place  Sketch 

It  is  often  necessary  to  sketch  a  certain  area  from  one  point  of  observation. 
This  is  called  a  Place  Sketch.  It  is  also  made  on  the  same  scale  and  with  the  same 
V.I.  as  the  position  sketch. 

In  time  of  war  there  is  a  great  demand  for  sketches  of  this  class  from  non-com- 
missioned officers.  Fig.  23  will  illustrate  the  method  of  construction  which  is  very 
simple.  However,  in  order  to  produce  a  Place  Sketch  of  value,  the  sketcher  must 
possess  the  ability  to  estimate  distances  with  less  than  ten  per  cent  error  up  to  (600 
yards  and  with  fifteen  per  cent  up  to  a  mile.  The  sketcher  should  again  familiarize 
himself  with  the  rules  for  estimating  distances  as  given  in  the  "Small  Arms  Firing 
Regulations;"  Telephone  and  Telegraph  poles  are  usually  set  up  at  fixed  distances 
which  often  will  be  of  great  assistance.  In  many  parts  of  the  country  the  land  is 
divided  into  sections,  and  the  sections  sub-divided  in  such  a  manner  as  will  aid  the 
sketcher  in  making  correct  estimations. 

As  estimations  of  distances  are  made  in  yards,  a  working  scale  of  yards,  6  inches 
equals  1  mile,  is  necessary.  Such  a  scale  will  be  found  on  the  Universal  Rule  for 
Military  Sketching  and  Map  Reading. 


Construction  of  Place.  Sketch 

Your  instructor  directs  that  you  go  to  a  point  A,  and  make  a  Place  Sketch  in- 
cluding the  area  within  a  radius  of  one-half  mile  of  A  and  east  of  a  N.  and  S.  line 
through  A. 

The  sketcher  proceeds  to  A,  orients  the  board  with  the  needle.  He  looks  over 
the  area  to  be  sketched  and  picks  out  the  critical  points  C  and  D,  first  getting  their 
direction  and  then  laying  off  the  distance  by  estimation.  By  counting  the  telephone 
poles  he  will  be  able  to  determine  the  distance  C  D  which  may  be  used  as  an  aid  in 
estimating  other  distances.  He  extends  the  road  E.  from  D  and  W,  from  C.  With 
this  base  carefully  plotted,  he  is  able  to  sketch  in  the  river,  creek,  rail-road  station, 
rail-road,  houses  and  bridges.  If  he  has  field  glasses  he  will  be  able  to  ascertain  the 
construction  and  make  a  very  close  approximation  of  the  dimensions  of  the  bridges. 

Now  he  wishes  to  represent  the  hills  and  valleys. 

Naturally  the  lowest  part  of  his  sketch  is  down  stream  part  of  Green  River. 
This  is  his  datum  plane.  For  convenience  he  calls  this  zero.  He  carefully  estimates 
the  distance  to  O,  reads  his  slopes  and  with  his  scale  of  M.  D.  determines  his  elevation 
at  A.     He  then  spaces  in  the  contours  between  A  and  O.     In  a  similar  manner  these 


FOR  NON-COMMISSIONED  OFFICERS  63 

contours  are  prolonged  so  as  to  include  the  entire  sketch.  Vegetation  and  other 
important  details  are  noted. 

In  no  other  way  could  this  soldier  convey  as  much  information  to  his  commanding 
officer.  By  sending  several  good  sketchers  out  to  various  points  the  commanding 
officer  will  soon  have  before  him  a  very  good  map  of  the  surrounding  country. 

After  the  above  has  been  carefully  explained,  the  instructor  will  post  each  member 
of  the  class  in  the  same  locations  as  he  might  the  outguards  of  an  outpost,  and  require 
each  man  to  make  a  place  sketch  including  a  certain  well-defined  area  to  the  front 
of  his  position.  When  the  sketches  are  completed,  they  will  be  turned  in  and  the 
class  dismissed. 

The  following  lesson  (XXVII),  the  instructor,  accompanied  by  the  entire  class, 
will  proceed  in  turn  to  each  of  the  positions  occupied  by  the  sketchers  on  the  previous 
day.  Members  of  the  class  other  than  the  sketcher  who  occupied  the  position 
will  be  required  to  orient  the  sketch,  both  by  compass  and  by  known  points,  to  check 
the  directions,  distances,  and  in  fact  review  the  entire  sketch.  By  this  method  many 
points  will  be  brought  out,  and,  at  the' same  time,  every  man  will  be  keen  to  do  his 
best,  knowing  that  his  work  is  to  be  reviewed  by  the  entire  class. 


64 


Military  Sketching  and  Map  Reading 


PLACE    SKETCH 

VACINITY    Of   GRF.CN  RIVER  AND  TROUT    Cr 
Observations    made  from   A. 


o         fcgg         gag  tqoo  Td* 


M.    10    ft 


Fig.  23 


FOR  NON-COMMISSIONED  OFFICERS  65 


LESSON  XXVIII 


Visibility 

It  is  often  necessary  to  determine  from  the  map  whether  one  point  is  visible 
from  another;  whether  a  certain  line  of  march  is  concealed  from  the  enemy;  how 
much  of  a  certain  area  can  be  seen  from  a  given  point ;  and  whether  slopes  are  uni- 
form, concave  or  convex.  If  the  map  is  correct  the  above  information  can  be  deter- 
mined very  accurately  in  the  following  manner: 

See  Map  A. 

1st.  By  studying  Map  A  in  connection  with  the  Model,  Fig.  15,  the  following  prin- 
ciples of  visibility  are  obvious : 

(a)  Contours  closely  spaced  on  the  top  of  a  hill,  and  gradually  getting  farther  apart 
toward  the  bottom,  as  H  I  J  K,  show  a  concave  slope,  and  all  points  of  the  intervening 
surface  are  visible  from  both  the  top  and  bottom  of  the  slope. 

(b)  Contours  spaced  far  apart  at  the  top  and  gradually  closer  toward  the  bottom, 
as  L  M  N  O  P,  show  a  convex  slope,  and  neither  end  of  the  slope  is  visible  from  the  other. 

(c)  Parallel  contours  equally  spaced  as  e  f  g  h,  indicate  a  plane  surface,  and  all  inter- 
vening points  are  visible  from  top  to  bottom  of  the  slope. 

Bearing  the  above  principles  in  mind,  one  is  often  able  to  tell  at  a  glance  whether 
or  not  one  point  can  be  seen  from  another.  If  visibility  cannot  be  determined  by 
eye,  the  simple  method  explained  later  in  the  lesson,  can  always  be  relied  on. 

Visibility  problems  may  be  divided  into  three  classes: 

1st.      To  determine  whether  or  not  one  point  is  visible  from  another. 
2nd.    To  determine  how  much  of  the  ground  line  connecting  the  two  points  is  visible 
from  either  point. 

3rd.    To  determine  how  much  of  a  certain  area  is  visible  from  a  given  point. 

With  an  understanding  of  the  three  principles  of  determining  visibility  by  inspec- 
tion, and  the  ability  to  solve  the  three  problems  noted  above,  the  student  will  be 
prepared  to  solve  any  visibility  problems  that  may  arise.  Each  member  of  the  class 
should  become  familiar  with  the  method  of  solving  point,  line,  and  area  problems  in 
visibility  as  explained.     (See  Map  "B,"  Fig's.  3,  4,  5,  and  6.) 


6<5  MILITARY  SKETCHING  AND   MAP  READING 


LESSON  XXIX 


Visibility  (Continued) 

The  instructor  should  issue  the  best  available  contoured  map  of  the  surrounding 
country  to  each  member  of  the  class.  (The  Geological  Survey  Maps  are  excellent 
for  this  purpose.)  Each  man  should  be  required  to  solve  problems  involving  the 
visibility  of  points,  lines,  and  areas  from  some  selected  point  of  observation  on  the 
map.  The  results  should  be  verified  by  the  instructor  and  retained  for  comparison 
with  the  ground  features  in  the  following  lesson. 

LESSON  XXX 

The  instructor  should  now  march  the  class  to  the  point  of  observation  selected 
in  the  previous  lesson  and  each  man,  after  orienting  his  map,  will  compare  the  actual 
visibility  of  points,  lines,  and  areas  with  his  results  of  the  previous  lesson.  In  this 
manner  the  accuracy  of  the  map  as  to  contours  can  readily  be  determined. 


FOR  NON-COMMISSIONED  OFFICERS  67 


APPENDIX 


Construction  of  Scale  of  Paces 

Sergt.  Jones  paces  a  course  of  a  thousand  yards  four  times  with  the  following 

results: 

1st  result,  1118  paces. 

2nd  result,  1109  paces. 

3rd  result,  1120  paces. 

4th  result,  1117  paces. 

He  wishes  to  construct  a  working  scale  of  paces,  3  inches  on  the  scale  represent- 
ing one  mile  on  the  ground. 

To  do  so  he  should  proceed  as  follows: 

1st.  Find  the  length  of  his  pace. 

2nd.  Find  out  how  many  of  his  paces  will  be  represented  by  one  inch  on  the  map. 

3rd.  Find  the  length  in  inches  of  his  working  scale. 

4th.  Construct  the  scale. 

1st.    To  find  the  length  of  his  pace : 

1118 
1109 
1120 
1117 


4464-7-4  =  1116  paces  (average  number  of  his  paces  for  1,000  yards). 
1,000  yds.  =  36,000  inches. 

36,000-7-1116  =  32.2  inches  the  length  of  his  pace.     (If  the  decimal  is  .5  or  less  use 
the  number  below,  if  greater  than  .5  use  number  above.) 

Sergt.  Jones'  pace  is  32  inches  long. 

2nd.    To  find  out  how  many  of  his  paces  will  be  represented  by  one  inch  on  the 
map. 

3  inches  on  map  =  63,360  inches  on  ground. 

1  inch  on  map  =  21,120  inches  on  ground  or  (21,120-7-32)  =660  of  his  paces. 

3rd.     To  find  the  length  in  inches  of  a  convenient  working  scale  representing 
say  2,400  paces: 

660  paces  =  1  inch. 

2400-7-660  =  3.63  inches  =  length  of  scale. 

4th.    To  construct  the  scale: 

Lay  off  the  line  A  B,  3.63  inches  long,  which  represents  2,400  paces. 

Divide  this  line  into  24  equal  divisions  representing  100  paces  each. 

Divide  the  first  one  of  these  smaller  parts  into  five  equal  divisions  of  20  paces 


68  MILITARY  SKETCHING  AND   MAP  READING 

each.     (See  Fig.  a.)     Transfer  these  sub-divisions  to  the  Universal  Rule  and  the 
scale  is  completed. 

To  divide  the  line  A  B,  Fig,  a,  into  24  equal  divisions,  lay  off  any  line  A  C  that 
can  be  conveniently  divided  into  24  equal  parts.  Connect  B  C,  then  draw  lines 
parallel  to  B  C  as  shown  in  Fig.  a.  These  will  divide  A  B  into  24  equal  parts  each 
representing  100  paces.     Use  the  same  method  for  divisions  representing  20  paces. 

Method  of  Constructing  Drawing-Board  with  Tripod  and  Prime 

Attachment  for  Reading  Slopes 


The  Drawing-Board 

The  drawing-board  should  be  of  soft  pine  13"xl4"  and  1  inch  thick.  This 
will  allow  a  drawing  surface  sufficient  to  include  four  square  miles  of  position  sketch 
and  enough  extra  space  to  secure  the  paper  to  the  board. 

The  Tripod 

Take  a  piece  of  "Two  by  four"  five  inches  long.  (See  Fig.  b)  and  three  sticks 
4'xl"xK"i  the  latter  of  some  tough  material  which  will  not  be  easily  broken. 
About  Y$  inch  from  the  end  of  these  sticks  bore  holes  yi  inch  in  diameter. 

At  the  middle  of  one  end  of  the  block  saw  out  a  slit  yA  inch  wide  and  extending 
\}4  inches  into  the  block.  By  means  of  wire  nails  driven  as  shown  in  Fig.  c  attach 
the  three  legs  to  the  block,  one  leg  in  the  slit  and  the  remaining  two  legs  at  the  other 
end  of  the  block.  Then  drive  a  wire  nail  into  the  centre  of  the  bottom  of  the  block ; 
the  nail  being  of  sufficient  length  so  that  it  will  protrude  y  of  an  inch  out  of  the 
block,  (see  Fig.  c).  When  all  of  this  has  been  completed  you  will  have  a  tripod 
something  like  Fig.  d.  Now  bore  a  hole  y  of  an  inch  deep  into  the  center  of  the 
bottom  of  your  drawing-board,  the  diameter  of  this  hole  being  just  sufficient  to 
accommodate  the  wire  nail  protruding  from  the  top  of  the  tripod.  Now  attach  the 
drawing-board  to  the  tripod  by  means  of  the  nail  and  hole  just  described  and  you 
will  have  a  drawing-board  and  tripod  complete,  by  means  of  which  the  board  can 
be  quickly  oriented  and  leveled,  also  the  board  is  easily  detached  from  the  tripod 
when  it  becomes  necessary  to  read  angles  of  slope. 

Attachments    for  Reading    Angles  of   Slope 

See  Lesson  XIII,  Fig.  17.  This  attachment  should  be  constructed  at  the  same 
time  that  the  drawing-board  and  tripod  are  made  in  order  to  be  ready  for  use  when 
required. 


FOR  NON-COMMISSIONED  OFFICERS 


69 


Fig.  A 


70 


MILITARY  SKETCHING  AND  MAP  READING 


Fig.b 


Fig.  c 


4-v 


/hjL.t!    -4-,  o , 


S5  7333 
MAR    26jy33 


MAY  12  11 


<3L 


3DH 


tD2j 


«0, 


"»-V3f 


« 


YE  0034 


-■•  I     UN,..!.  ||  ^w^wm 


